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Emacs provides several commands for sorting text in the buffer. All
operate on the contents of the region.
They divide the text of the region into many sort records,
identify a sort key for each record, and then reorder the records
into the order determined by the sort keys. The records are ordered so
that their keys are in alphabetical order, or, for numeric sorting, in
numeric order. In alphabetic sorting, all upper-case letters ‘A’
through ‘Z’ come before lower-case ‘a’, in accordance with the
ASCII character sequence (but
described below, can change that).
The various sort commands differ in how they divide the text into sort records and in which part of each record is used as the sort key. Most of the commands make each line a separate sort record, but some commands use paragraphs or pages as sort records. Most of the sort commands use each entire sort record as its own sort key, but some use only a portion of the record as the sort key.
Specify which field to sort by with a numeric argument: 1 to sort by
field 1, etc.; the default is 1. A negative argument means count
fields from the right instead of from the left; thus, minus 1 means
sort by the last field. If several lines have identical contents in
the field being sorted, they keep the same relative order that they
had in the original buffer.
sort-numeric-base, but numbers beginning with ‘0x’ or ‘0’ are interpreted as hexadecimal and octal, respectively.
For example, if the buffer contains this:
On systems where clash detection (locking of files being edited) is implemented, Emacs also checks the first time you modify a buffer whether the file has changed on disk since it was last visited or saved. If it has, you are asked to confirm that you want to change the buffer.
applying M-x sort-lines to the entire buffer produces this:
On systems where clash detection (locking of files being edited) is implemented, Emacs also checks the first time you modify a buffer saved. If it has, you are asked to confirm that you want to change the buffer. whether the file has changed on disk since it was last visited or
where the upper-case ‘O’ sorts before all lower-case letters. If you use C-u 2 M-x sort-fields instead, you get this:
implemented, Emacs also checks the first time you modify a buffer saved. If it has, you are asked to confirm that you want to change the buffer. On systems where clash detection (locking of files being edited) is whether the file has changed on disk since it was last visited or
where the sort keys were ‘Emacs’, ‘If’, ‘buffer’, ‘systems’ and ‘the’.
M-x sort-columns requires more explanation. You specify the columns by putting point at one of the columns and the mark at the other column. Because this means you cannot put point or the mark at the beginning of the first line of the text you want to sort, this command uses an unusual definition of “region”: all of the line point is in is considered part of the region, and so is all of the line the mark is in, as well as all the lines in between.
For example, to sort a table by information found in columns 10 to 15,
you could put the mark on column 10 in the first line of the table, and
point on column 15 in the last line of the table, and then run
sort-columns. Equivalently, you could run it with the mark on
column 15 in the first line and point on column 10 in the last line.
This can be thought of as sorting the rectangle specified by point and the mark, except that the text on each line to the left or right of the rectangle moves along with the text inside the rectangle. See Rectangles.
Many of the sort commands ignore case differences when comparing, if
sort-fold-case is non-